Asteroids Detection Tehnique: Classic “Blink” An Automated Approch Denisa Copândean, Ovidiu Văduvescu Constantin Nandra, Dorian Gorgan, Isaac Newton Group of Telescopes (ING), Computer Science Department Santa Cruz de la Palma, Canary Islands, Spain Technical University of Cluj-Napoca Cluj-Napoca, Romania Instituto de Astrofisica de Canarias (IAC), {denisa.copandean, constantin.nadra ,dorian.gorgan} La Laguna, Canary Islands, Spain @cs.utcluj.ro [email protected] Abstract—Asteroids detection is a very important research predictions of the future trajectories of the discovered objects. field that received increased attention in the last couple of The Program also supports efforts to characterize a decades. Some major surveys have their own dedicated people, representative sample of NEOs by measuring their sizes, equipment and detection applications, so they are discovering shapes, and compositions. NASA’s Authorization Act of 2005 Near Earth Asteroids (NEAs) daily. The interest in asteroids is goal is to detect, track, catalogue, and characterize the physical not limited to those major surveys, it is shared by amateurs and characteristics of 90 percent of the NEO population with mini-surveys too. A couple of them are using the few existent diameter sizes larger than 140 meters by 2020. While the major software solutions, most of which are developed by amateurs. American surveys have increased the discovery rate, in Europe The rest obtain their results in a visual manner: they "blink" a there are just a few local initiatives led by some scientists, sequence of reduced images of the same field, taken at a specific without specific funding or dedicated facilities. time interval, and they try to detect a real moving object in the resulting animation. Such a technique becomes harder with the Recently, ESA (European Space Agency) has begun to increase in size of the CCD cameras. Aiming to replace manual contract some European services to contribute to SSA (Space detection, we propose an automated "blink" technique for Situational Awareness) program. NEODyS at the University of asteroids detection. Pisa, KLENOT at the Klet Observatory, some national space agencies and other space industry entities are involved. Over Keywords—detection; asteroids; blink, cross objects, MPC; the past few years, the SSA program used the one-meter telescope ESA-OGS in Tenerife for some NEO studies and I. INTRODUCTION further analysis [2][3]. The European Near Earth Asteroids Asteroids are not just a source of information about the Research (EURONEAR) project has been contributing to this origin of our Solar System or an opportunity for mining research since 2006. EURONEAR includes only a small resources and modeling new frontiers for emerging space number of professional astronomers, involving more amateurs industry, they also represent a real threat for Earth, some of and students who promptly reduce the data, report discoveries them having a high risk of collision with our planet. Near Earth and perform NEA recoveries. By manually "blinking" a set of objects (NEOs) discovery is a very difficult task because they consecutive images of the same field, they made 9 important have a small size, poor magnitude and some of them have discoveries and multiple of asteroids recoveries. Their actions move at high speeds. Monitoring the nearby space for near Earth asteroids is essential for the future of our planet. Planetary defense is the term used to encompass all the capabilities needed to detect the possibility of potential asteroid or comet impacts with Earth and to warn the population, its’ purpose to either prevent these impacts or to mitigate their possible effects [1]. NASA (National Aeronautics and Space Administration) has been studying NEOs since the 1970s. The Agency initiated a survey, commonly called “Spaceguard,” in the 1990s to begin searching for them. NASA participated in the International Spaceguard Survey, initiated in 1996 and sponsored by the multinational Spaceguard Foundation. NASA's NEO Observations Program supports NEO surveys that contribute to a sustained and productive campaign to find and track NEOs, collecting data of sufficient precision to allow accurate Fig. 1. NEA discoveries in time (https://cneos.jpl.nasa.gov/stats/totals.html) were not part of an official NEA detection survey. Starting with the Near-Earth Asteroid Tracking (NEAT) program in 1995 a "step-stare" technique was implemented for Having this manual flow in mind, we propose an automated asteroids detection [7]. A step-stare system takes multiple pipeline prototype for moving object detection. The prototype images, each being exposed while the telescope tracks along is a modular system written in Python programming language, the Earth rotation. Then it was transferred to a computer before except for the Cross Object module which is written in Java the next exposure was taken. This technique produced better programming language. Each module has a specific results than a drift-scan technique and so it was further used by functionality, and some of them are tightly coupled to some rd other surveys that followed. The Lincoln Laboratory’s Near- other 3 party astrophysics libraries. Earth Asteroid Research (LINEAR) program run by the MIT The next section will presents some similar systems. Lincoln Laboratory takes for their detection software five Section 3 will consist of a short description of the correction images, 30 minutes apart. It only requires three hits for a modules for the proposed automated pipeline prototype and a detection [8]. more detailed description of the asteroids detection technique Variable KD-Tree algorithms were used by the Pan- used in Cross Object module. Some results and the influence of STARRS Moving Object Processing System [9], [10]. These the most important parameters involved in the detection techniques were developed in collaboration with the incoming prototype are presented in Section 4. The last section concludes LSST (Large Synoptic Survey Telescope) [11]. on the achievements and experiments, presents the work currently in progress, and sketches some future research It was not only the major surveys that developed automated directions. systems for moving object detection, but also some amateurs and small private surveys. For example, a group from II. RELATED WORKS Argentina developed such a system based on the profile of each light source represented by FWHM (Full Width at Half While making a star map, the Italian priest and astronomer Maximum) [12]. Giuseppe Piazzi accidentally discovered the first asteroid, Ceres, orbiting between Mars and Jupiter. Today, Ceres is classified as a dwarf planet, having been considered the III. AUTOMATED PROTOTYPE FOR ASTEROID DETECTION missing planet of the Bode's law. Bode's law suggested there The current version of the proposed pipeline prototype is should be a planet between Mars and Jupiter. It was discovered tightly coupled with the data obtained from the 2.5 meters based on its motion relative to the fixed background stars in a diameter Isaac Newton Telescope (INT) located in La Palma, couple of nights. Canary Islands, Spain. At the prime focus of the INT, a wide The same approach has been used from then on in asteroids field camera (WFC) is located, consisting of four CCDs of 2k detection, with evolved versions supported by the current x 4k pixels, covering an L-shaped 34 arcminutes x 34 -1 time’s technologies. In 1984, the Spacewatch group at the arcminutes field with a pixel scale of 0.33 arcseconds pixel . University of Arizona’s Lunar and Planetary Laboratory has A. Short Introduction on the Pre-process Modules used this approach to implement the first computer detection system based on CCD (change coupled device) [5]. Their Figure 2 presents the architecture of the prototype. The first two modules were developed in the Python programming automated "Moving Object Detection Program" (MODP) rd searched for objects showing consistent motion in three language are based on a couple of external (3 party) successive scans over the same region. Each scan was 30 astrophysics libraries for image reduction and field correction minutes long. During the first and second pass, their MODP [13]. recognized fast moving objects by the trails they left in the Any image taken by a CCD camera through a telescope image. A moving object was detected on the third pass based will not give accurate information about the photometric on the displacement of its position in the first two passes distribution over a portion of the sky. Optical imperfections relative to its position in the third pass [6]. So they developed a and the discrete nature of light itself lead to errors in the drift-scan technique. measured data. The first module corrects artifacts (bias, flat Fig. 2. Prototype Architecture field) and instrumental defects (bad pixels) from the raw. The equatorial coordinate system is a celestial coordinate system used to specify the positions of celestial objects. The The second module of the prototype solves the field equatorial coordinate system is using spherical coordinates. distortion issue of the reduced images in a sequence of steps Earth is at the center of the celestial sphere, an imaginary based on a few external astrophysics libraries. Substantial field surface on which the planets, stars, and nebulae seem to be distortions caused by the optical system and projection of a printed. The equatorial coordinate system is basically the hemispherical field into a 2D image occur in the imaging projection of the latitude and longitude coordinate system we process, especially at the prime focus of any larger field use here on Earth onto the celestial sphere. The right ascension telescope, which makes it difficult to perfectly align images for (RA, symbol α) corresponds to east/west direction like further processing and analysis. Field distortions increase with longitude, while declination (DEC, symbol δ) measures distance from the center of the image. north/south directions, like latitude. RA is measured in hours, The first two blue-colored modules from the architecture minutes and seconds eastward along the celestial equator.